STEPHEN W. PORGES

Department of Human Development, University of
Maryland, College Park, USA

Copyright, 1995 Society for Psychophysiological Research

PRESIDENTIAL ADDRESS, 1994

Abstract

The vagus, the 10th cranial nerve, contains pathways that contribute to
the regulation of the internal viscera, including the heart. Vagal efferent
fibers do not originate in a common brainstem structure. The Polyvagal Theory
is introduced to explain the different functions of the two primary medullary
source nuclei of the vague: the nucleus ambiguus (NA) and the dorsal motor
nucleus (DMNX). Although vagal pathways from both nuclei terminate on the
sinoatrial node, it is argued that the fibers originating in NA are uniquely
responsible for respiratory sinus arrhythmia (RSA). Divergent shifts in RSA
and heart rate are explained by independent actions of DMNX and NA. The theory
emphasizes a phylogenetic perspective and speculates that mammalian, but not
reptilian, brainstem organization is characterized by a ventral vagal complex
(including NA) related to processes associated with attention, motion,
emotion, and communication. Various clinical disorders, such as sudden infant
death syndrome and asthma, may be related to the competition between DMNX and
NA.